Combination center-square.



P. H. ALLISON.

COMBINATION CENTER SQUARE. APPLICATION I'ILBD JAN. 2, 1909.

Patehted Sept. 14,1909.

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UNITED STATES PATENT onnicn.

COMBINATION CENTER-SQUARE Application filed January 2, 1909.

ing the center of round'work, for laying out angles and for use as aT-square, depth gage and scale.

For the purpose mentioned the instrument is provided with a blade and ahead thereon, having apertures disposed on opposite sides of a linecoinciding with the inner edge of the blade, and removable pins forengagement with the said apertures to bring the pins and the edge of theblade in desired relative positions.

A practical embodiment of the invention is represented in theaccompanying drawings forming a part of this specification, in whichsimilar characters of reference indi-. cate corresponding parts in allthe views.

Figure 1 is a perspective view of the improvement; Fig. 2 is a plan Viewof the same, parts being in section, and showing the instrument asapplied for centering a round piece of work; Fig. 3 is a cross sectionof the same on the line 3-3 of Fig. 2 and showing the instrument appliedto a piece of work of small diameter; and Fig. 4: is a plan view of theimprovement and showing the various angles that can be accurately laidout by the use of the instrument.

The blade A of the measuring instrument terminates at one end in a headB extending on opposite sides of the inner edge A. of the blade A, asplainly shown in the drawings. The head B is provided with pairs ofapertures O, G and C C of which the apertures C, O are disposedequidistant on opposite sides of a line coinciding with the inner edgeA, and the apertures C G are similarly disposed equidistant on oppositesides of the inner edge A, but the apertures C, C are nearer togetherthan the apertures C C An auxiliary aperture (1* is also arranged on thehead B a distance forward of the aperture C The apertures O, C areadapted to be engaged by removable head pins D, D, and similar pins D DSpecification of Letters Patent.

Patented Sept. 14, 1909.

Serial No. 470,396.

y are adapted to be engaged with the apertures C C and any one of thepins may be insorted in the aperture C. 1 Now when it is desired to findthe center of a round piece of work E of large diameter, as shown inFig. 2, then use is made of the two pins D D and the instrument isapplied to the work E, so that the pins D 1) engage the peripheral faceof the work E and the blade A extends across the end to be centered. Nowlines are drawn along the edge A across the end of the work E, and theintersection of the lines indicates the center of the wor E.

When it is desired to find the center of a small piece of work E use ismade of the pins 1), D in the same manner as above described relative tothe work E and the pins D D By using the pins D, D for instance, whilethe other pins D, D are removed, an angle of 45 may be drawn relative tothe edge against which the said pins D and D abut, and angles of and 30may be drawn by inserting the pin D in the aperture 0* and using thispin D in connection with the pin D inserted in the aperture C. In a likemanner an angle of 60 may be drawn by the use of pins in the apertures Cand C, it being understood that the angles are drawn along the inneredge A of the blade A.

It will be understood that the arrangement of the apertures C, C, C andC with respect to the edge A is such that a line drawn through thecenters of the openings 0, C will form upon the side adjacent to theopening C an angle of 15 with the edge, while on the opposite side theangle will be 135. The arrangement of the openings G, C with respect tothe edge is the same. The arrangement of the opening C and the opening Gwith respect to the edge is such that a line drawn through the centersof C, C will make an angle of 30 with the edge on the side toward theopening C,

. movable engagement with The measuring instrument shown and describedis very simple and durable in c011- struction, and by the use of theremovable pins in the several apertures the instrument can be readilyused for accurately determining the center of round work, for laying outangles and for using the instrument as a square, depth gage, scale andthe like.

The lines shown in Fig. 4, extending outside of the instrument andmarked 45, are lines that may be laid out by the instrument relative toan arbitrary line which may be considered as the base.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

1. A measuring instrument comprising a head and a blade havinga straightedge and extending from the head, said head having detachable pinsconnected therewith and ar ranged in pairs, the members of each pairbeing arranged upon opposite sides of the straight edge of the blade andat equal dis tances therefrom, and in such manner that the linesconnecting the centers of the members of a pair will intersect the edgeat a right angle.

2. A measuring instrument comprising a blade, a head on one end of thesaid blade and having pairs of apertures, the apertures of each pairbeing spaced equidistant on opposite sides of a line coinciding with theillner edge of the said blade, and pins for rethe said apertures.

3. A measuring instrument comprising a blade, a head 011 one end of thesaid blade and having pairs of apertures, the apertures of each pairbeing spaced equidistant on opposite sides of a line coinciding with theinner edge of the said blade, the distances between the apertures of thesaid pairs of apertures varying for larger and smaller work, and pinsfor removable engagement with the said apertures.

at. A measuring instrument comprising a blade, a head on one end of thesaid blade and having pairs of apertures, the apertures of each pairbeing spaced equidistant on opposite sides of a line coinciding with theinner edge of the said blade, the said head also having an auxiliaryaperture, and pins for removable engagement with the said apertures.

5. A measuring instrument comprising a head and a blade having astraight edge and extending from the head, the head having a series ofopenings upon each side of the straight edge, the individual members ofwhich are arranged at different distances from the edge, the arrangementof the members of the series on one side being symmetrical with thearrangement of the series of the members on the other side, and a pairof pins for engaging the openings.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

Witnesses: 4

EDWARD W. MORGAN, DANIEL McDoUeALL.

